This commit adds:
1) Methods to SSLContext class that match CPython signature:
- `SSLContext.load_cert_chain(certfile, keyfile)`
- `SSLContext.load_verify_locations(cafile=, cadata=)`
- `SSLContext.get_ciphers()` --> ["CIPHERSUITE"]
- `SSLContext.set_ciphers(["CIPHERSUITE"])`
2) `sslsocket.cipher()` to get current ciphersuite and protocol
version.
3) `ssl.MBEDTLS_VERSION` string constant.
4) Certificate verification errors info instead of
`MBEDTLS_ERR_X509_CERT_VERIFY_FAILED`.
5) Tests in `net_inet` and `multi_net` to test these new methods.
`SSLContext.load_cert_chain` method allows loading key and cert from disk
passing a filepath in `certfile` or `keyfile` options.
`SSLContext.load_verify_locations`'s `cafile` option enables the same
functionality for ca files.
Signed-off-by: Carlos Gil <carlosgilglez@gmail.com>
Carlosgg